Isolation of isolactarane sesquiterpenes from a culture filtrate and their growth promotion effects on lettuce roots.

The ethyl acetate extract of the culture filtrate of promoted elongation of the lateral roots of lettuce seedlings at 250 µg/mL. We purified two compounds that promote root elongation by using activity-guided chromatographic fractionation. On the basis of spectroscopic analyses, these compounds were identified to be isolactarane sesquiterpenes derived from the dehydrogenation of merulactone, which was previously isolated from the same species.